The commission’s proposal may make the surplus of allowances even worse closer to 2020 as withheld permits are released back to the market, said Daniel Rossetto, director of Climate Mundial Ltd., a London-based adviser on carbon markets. “Back-loading won’t fix the problem,” he said in a March 28 e-mail. If the bloc abandons the plan, policy makers must reassure the market they will adopt a better fix as soon as possible, he said. A unified statement from the commission, parliamentarians and nations “would avert a big sell-off if people know that back-loading is being ditched to make way for a more comprehensive reform,” Rossetto said.